@Remi-le-Oduen I thought about this too, but the news post says that completely original means that you can not include characters from other media and says nothing about setting (I know this is kind of splitting hairs). R'lyeh is merely a place in Lovecraft, and is only mentioned in the story, but not necessarily the setting where it takes place ;)
(I could even change the name from R'lyeh to some other fictitious place I made up and it'd work perfectly fine, but I liked the idea of mentioning it in the story.)
That being said, I'm glad you like it!
Remi-le-Oduen
The one from @Yeelp is good, but can it be considered original if it takes place in Lovecraft's R'lyeh?